Railway signaling system



' `lune 15, 1943,.

H. A. THOMPSON RAILWAY SIGNALING SYSTEM Fi1ed..uarch 25. 1941 2 Sheets-Sheet 1 sw@ QQ www# su@ s@ June 15, 1943. H. A. 'rr-xo/IFSON` RAILWAY SIGNALING SYSTEM 2 Sheets-Sheet 2 Filed March 25, 1941 771omps0n Patented June 15, 1943 U N i T E D STAT-'E S PATE N T O'FF-lflC RAILWAY. SIGNALING SYSTEM- Howard A. Thompson, Edgewood, Ba., assignor to The Union Switchl y8p Signal 'Companyi Swissvale, Pa., a corporation of Pennsylvanial Application Marchas, 1941, serial No. 385.939

1 Cllaim.

My invention relates to railwaysignaling systems and moreparticularly to systems of the type*v known as the continuous inductive track circuit type employing alternating current .of a plurality of frequencies.

It is an object of my invention to proyidevaasystem of the type described andI incorporating improvedl means for controlling crossing, signalsl which protect the highway crossings in the track stretch n which the systemv is employed.

A further object -of myinvention is t0 plOVideasignal system of the typedescribed employing energy of two frequencies to control the vehicle carried signal apparatus and employing .energy of a lthird frequency to discontinue operationof ag crossing signal.

Another object of my invention is to provide asignal system of the type described employing; energy of a plurality of diiferent frequenciesvto..

control vehicle carried signal apparatus andin-.V`

corporating means for at times .modifying the;

energy of. one of these frequencies to provide means to control a crossing signal.. v

A further object of the invention is toprovide;

asystem of the typedescribed and incorporating` improved means for use at a cut section forsup?V plying to the section in the rearof the .cut section.

energy of the same frequency as is supplied Ato the section in advance of the cut.

Another object of my invention is. to. provide an improved railway signaling system.

Other objects of my invention and features of novelty will be apparent from the following de scription taken in connection with the accompanying drawings.

I shall describe two forms of railway signaling-v systemv provided by my invention, and shallvthen point out the novel features thereof in claims:

In the drawings Fig. 1 is a diagram of'a railway signaling' system embodying my invention, andl Fig. 2 is a diagram of a modified -form of vrail-i way signaling .system embodying -my invention.

Similar reference characters -refer 'to -similar g parts in each of the two views.

Referring to Fig. 1 of thedrawings, there isshown therein a stretchV of railroadftrackihaving track rails I and'2,over which-trafcnormally moves in the direction indicated bythe'. arrow, that is from left to, right.

The rails of the track stretch are divided by in.-

sulated joints 3 into the customary successive V track sections.

The portionfof the trackstretclr shown inthe drawings includes an intersection with a highway,.and to 'provide .for control of the.l

crossing lsignals XS which protect -theyhighway intersection, the rails $of .the track section whiclrv inludes. the. highway intersection are. divdedby.. insulated .joints asinto an. approach. subsection; A.I2T=.and a clearing subsectiong|5il2T'. Theadg. jacent section in. the rearis designated] ll'ffwhile theadjacent sectionin advance vis designated] 3'1".

The; system shown inthe, drawingsis; intended to provide the clear indication, while 100cyc1e5= energy supplied from4 such source byu tuned alter.- nators or equivalent -devices is employedl toprof vide the caution-indication...

They cab signalapparatus is, designed to Adis-v tinguish` between` the .two frequencies tof. altere nating current. Theconstructionof thev cab sig: nal equipment is not anparttoflgthis inventionandy.

anyform .of equipment well knownin; the art may be .employed for this purpose. One .form..of equip.

ment whichgmaybe.. used is shown'y in; United/5.

StatesPatent No. 1,869,847,1issuedAugust 2 1932;'- to Lars O. Grondah'l-.i

The equipment is shown in the condition which.` itassumesvwhen the track jstretch-.is vacant.:r At

this time licycle alternating current energy is supplied-to the rails of-V section I3TL and feeds through .la y transformer SRTan'd j a rectiiier-| 3R57 to the. track relay.. |3TR lse Athat the contacts of this relay -are picked up;Y Contact 2- 20; therefore,

establishes v a circuiti to supply 60 .cycle energyf fromY nline 4transformera 13TH-to track transformer B'IZTT, while contact 2l `interruptsthe supplygf of energyV to av tuned :alternator-I STA' andY there@ by maintains this deyice idle; l

The 60 Cycle envengy-'A Supplied ,tOpthe, rails p0f.; section BI 2T feedsn to theV winding-21er a devicel nM Ywhich is .similar in.,.constructionpto aituned... alternates. but fdiers; therefmm .1. in that.. it. is not tuned oradjuslted to operate at a..parti.6111.54.12A

frequency, butis f adapted ..to.. operate. at., either of'ftrifrealiencs-.- The derieefM-falsofdi e; from-:aimed .alfematern that ,the vreed oem@ 1n Ithesystem shown 60,:Cy911- Y1QPgY;- froma commercialsource of current' is employed-.1v

from to the rails of section AI2T. The energy which is supplied to the track transformer is supplied from a line transformer BIZTB through a rectier RA.

In addition, when the reed or moving element of the device M is in its right-hand position the winding of a control relay CR is energized in multiple with one portion of the primary winding of transformer AI2TT, and contact 21 is picked up to interrupt the circuit of a code transmitter CT and to also interrupt a circuit including contact 240 of this device. Accordingly the code transmitterCT is maintained idle, and the device is constructed in such manner that its contact 240 is open at such times.

The 60 cycle energy supplied to the rails of approach section AI2T feeds to transformers D and E which in turn supply current to relays A-IZTR and F. These transformers operate as described in United States Patent No. 1,704,110 to Clarence S. Snavely to distinguish between energy of different frequencies. These transformers are proportioned so that when 60 cycle energy is supplied thereto each supplies suicient energy to its associated relay AI2TR or F to maintain the contacts of such relay picked up.

As the'contacts of relay AIZTR are picked up contact 20 establishes a circuit to supply 60 cycle energy from a line transformer AIZTB to a track transformer IITT for section IIT, while contact 2| interrupts the circuit of an alternator AIZTA.

'As the contact 30 of relay F is picked up a circuit is established to supply energy from transformer AIZ'IB through a rectifier RA to a v crossing signal control relay XA, and contact 28 of this relay is picked `up to interrupt the circuits of i the crossing signals XS and thereby maintain these signals inactive.

When a train moving in the normal direction oftraffic moves through the track stretch, the cab. signal. apparatus operates yto provide the green or clear indication in each track section if energy of 60 cycle frequency is supplied to the railscf such section.

When a train enters section AI2T, the relays A I 2TR and F release.v Release of contact 30 of relay FA interrupts the circuit ofthe relay XA and contact 28 of this relay releases and establishes the circuit of the crossing signals XS, and these signals operateto warnusers of the high- Wav 0f the approach Ofi.d train- 'In addition, on release of relay AIZTR contact 20 interrupts-the supply of 60 cycle energy from linetransforme AIZTB to the track transformer IITT, and establishes a circuit from the alternatorAIZTA to the track transformer. As contact Y2|'of relay AAIZTRQMis released a circuit is established to supply energy from the rectifier RA to the alternator vAI2TA so that the alternatorope'ratesto supply energy of 100 cycle frequencyto the track transformer I ITT.

lAccordingly, if after the train under consideration vacates-section IIT a second or following train enters section I IT, the cab signal equipment carried thereby will receive energy of cycle frequency and will provide its yellow or caution indication.

When the first train advances into section BI 2T the device M is shunted and ceases to operate with the result that energy is no longer supplied thereby to the transformer AIZTT or to the winding of relay CR. Contact 2l of relay CR, therefore, releases and establishes a circuit to supply energy from a rectifier RA to the operating winding of the code transmitter CT, while contact 2'! also establishes the circuit including contact 240 of code transmitter CT for supplying energy from the rectifier RA to the transformer AI2TT.

The code transmitter CT, therefore, operates and when its contact 240 is closed energy is supplied from the rectifier RA to the right-hand portion of transformer AI2TT, while the supply of energy to the transformer is interrupted when the contact 240 is open. The contact 240 is: operated at a rate such` as to provide 240 energy impulses a minute, so that alternating current of 4 cycle frequency is induced in the secondary winding of transformer AI2TT and is supplied therefrom to the rails of section AI2T.

When energy is supplied to the primary winding of transformer AI2TT over the circuit controlled by contact; 240 of code transmitter CT the rectifier K prevents the supply of energy to the relay CR so that this relay remains released and maintains the circuit of the code transmitter CT.

When the train vacates the approach section AI2T, the 4 cycle energy supplied to the rails of this section feeds to the transformers D and E. The transformer D is of such size that too little energy is supplied through it to pick up the relay AI2TR and this relay remains released so that energy of 100 cycle frequency continues to be supplied by alternator AIZTA to section IIT. The transformer E is of such size, however, that suflicient energy is supplied to the relay F to pick up this relay so its contact 30 establishes the circuit of the relay XA, and contact 28 of this relay picks up to interrupt the circuit of the crossing signals XS and thereby discontinue operation of these signals.

If while the first train is present in the clearing section BI2T a'second or following train should enter the approach section, the relay F will become released and interrupt the circuit of relay XA to thereby again effect operation of the crossing signals. However, the cab signal equipment on this following trainv will not respond to the 4 cycle energy present in the rails yto the transformer BIZTT. When section BIZT is vacated this energy feeds to the winding '23 of device M and causes the reed or moving element 25 of this device to operate lto alternately energize the, two portions of the primary winding of transformer vAI2TT at a rate such that 100 cycle energy is supplied to the rails of section AI 2T, while energy is supplied to relay CR and its contact 21 picks up to interrupt the circuit of the code vtransmitter CT and of the contact 24|) of this device so that it ceases to supply en ergy to the transformer AIZTT.

The 1 00 cycle energy supplied to the rails of section ,AIZT feeds to the transformers D and E. Suflicient energy continues to be supplied through the transformer E to maintain the relay F picked up, While sufficient energy is now supplied through the transformer D to pick vup the relay .AI2TR. When this relay picks up, the supply of 100 cycle energy to section IIT is discontinued and 60 cycle energy is supplied instead, whilev operation of the alternator AIZTA is discontinued.

I f, While a i'lrst train is present in section I3T, a second or following train should enter the approach section AI2T the cab signal apparatus carried by the train would respond to the 100 cycle energy in the track rails to provide theyellow or caution indication, while the track relays A12-TR and F would be released to effect operation of the crossing signals XS and to cause energy of 100 cycle frequency to be supplied to. the rails of section I IT.

When the rst train vacates section I3T, the track relay ISTR picks up and changes the energy supplied to section BI2T from 100 cycle to 6 0 cycle, While the device M responds to this change in the energy supplied thereto to supply energy of 60 cycle frequency to section AIZT.

Construction and operation of modificatie-n shown in Fig. 2

Referring now to Fig. 2 the equipment at the entrance end of section IST is the same as the corresponding equipment in the system shown in Fig. 1, but the equipment shown in Fig. 2 employs different means to discontinue operation of the crossing signals when a train vacates the approach section.

The equipment is shown in the condition which it assumes When the track stretch is vacant. At this time energy of 60 cycle frequency is supplied to the rails of section IST and track relay ISTR is picked up so that energy of this frequency is' supplied to the rails of section Blz'r. This energy is supplied through the transformer BIZRT and rectier BI2R to track relay BIZTR, while this energy also is supplied t the operating winding 23 of device M which is similar to the corresponding device employed in the system shown in Fig. 1. Accordingly relay BIZTR is Picked up and its contact 30 establishes connection from the secondary winding of transformer ST to the primary Winding of track transformer AIZTT, While its contact 3l interrupts the circuit of the code transmitter CT.

As energy of 60 cycle frequency is supplied to the winding of device M the reed or moving element 25 of this device establishes and interrupts the circuit for supplying energy from the rectifler RA to the primary winding of transformer yST at a rate such that energy of 60 cycle frequency is induced in the secondary Winding of Y this transformer and is supplied therefrom to the track transformer AlZTT.

The 60 cycle energy supplied to the track rails of section AIZT feeds through the transformer AIzRT and rectifier Alan to the relays G and A I'ZTR. As relay G is steadily picked up energy is not supplied through the decoding transformer AIZDT to the relay H and the contacts of this relay are released. Y

As relay AIZTR is steadily picked up its conillQ 32 establishes al circuit to supply energy dem the rectifier RA man. may Xaand. the '1s Contact 28 of relay interrupts the @inuit Qf the crossirl-ssienals XS t0 maintain these Slee nels inactiva Inaddition, contact 34 of relay AIZTR inter-` rupts theA supply of energy to the'alternator AIZTA, While contact 35 establishes the circuit to supply energy of 60 cycle frequency-'from line transformer AIZTBto track transformer IITT- so that renergy of 60 cycle frequency is supplied to the rails of section I IT.

When a train moving in the normal direction of trafc, that is from left to right, enters section IIT the cab signal apparatus carried thereby responds to the 60 cycle energy to provide the green or clear indication. Similarly when the train advances into each successive section the cab signal apparatus responds to the G0 cycle energy to provide the green or clear indication.

When the train enters approach section AIZT the track relays G andl AIZTR release. On re-y lease of contact 32 of relay AIZTR the supply of energy to the relay XA is interrupted and contact 28 of this relay releases and establishes the circuit of the crossing signals XS so that these signals operate to Warn users of the highway of the approach of a train.

On release of relay AI2TR contact 35 interrupts the supply of 60 cycle energy from line transformer AIZTB to the track transformer IITT, and establishes a circuit to permit 100 cycle energy from the alternator AIZTA to be supplied to the track transformer, While contact 34 establishes a circuit to supply energy from the rectifier RA to the alternator AIZTA so that the alternator operates and 100 cycle energy is supplied to the rails of section I IT.

On release of the contacts of relay G an impulse of energy is supplied through the decoding transformer AI2DT to the relay H, but the relay ff is somewhat slow to vpick up and does not become picked up on the supply of one impulse of energy thereto. Accordingly contact 3.1 of this relay remains released and does not establish a circuit to supply energy to the relay XA.

When the train advances into the clearing section BIZT the track relay BIZTR and the Winding 23 of device M are shunted so that relay BIZTR releases and device M ceases to operate. Release of Contact 30 of relay BIZTR establishes the circuit of code transmitter contact 15, while release of contact 3l of relay BIZTR establishes a circuit to supply energy from the rectifier RA to the winding of code transmitter CT. The code transmitter CT has a contact 15, which when the device is energized is operated between its released and picked-up positions at a suitable rate, such as times a minute, so as to provide 75 energy impulses per minute Which are separated by periods of equal duration during which no energy is supplied. Accordingly, the contact 'I5 of the code transmitter is operated and establishes a circuit to supply impulses of 60 cycle energy from the line transformer Bl 2TB to the transformer AI 2TT and thus to the rails of section AIZT. The circuit for supplying energy to the transformer AI2TT is traced from one terminal of the secondary winding of line transformer BIZTB throughv code transmitter contact '15, back contact 35 of relay BIZTR, and primary winding of transformer AIZTT to the other terminal of the secondary winding of line transformer BIZTB. A

When the train vacates the approach section AIZT the impulses of energy supplied through transformer AIZTT feedA to the relays G and AI2TR and cause alternate picking up and releasing of the contacts of these relays.

As a result of this code following operation of the contacts of relay G energy is supplied through the decoding transformer AI2DT to the relay I-I, and contact 3l of relay H picks up and establishes a circuit to supply energy from the rectifier RA to the relay XA so that contact 28 picks up and interrupts the circuit of the crossing signals XS which thereupon cease to operate.

In addition, at this time, contact 38 of relay H picks up and establishes a circuit shunting the winding of relay AIZTR so that this relay no longer responds to the coded energy. Instead its contacts remain released and maintain the :supply of 100 cycle energy from the alternator .AI ZTA to the transformer I ITT.

The relay H is of a type which is slow in releasing so that its contacts remain picked up during the intervals between the supply of impulses of energy thereto from the decoding transformer AI2DT.

If, while clearing section BI2T is occupied, a second or following train advances into section I IT the cab signal apparatus carried thereby will respond to the 100 cycle energy in the track rails to provide the yellow or caution indication. When the second or following train advances into the approach section AI2T the cab signal apparatus will respond to the coded 60 cycle energy in the section rails to alternately flash the green or clear lamp and the red or stop lamp. The flashing indication will be regarded as a block occupied signal by the operating rules for this track stretch.

If a train enters the approach section AIZT at a time when the clearing section BIZT is occupied, at which time coded energy is supplied to the rails of section AI2T, the track relay G will be shunted and will cease to follow code. This will cut off the supply of energy through the decoding transformer AI2DT to the relay H and the contact 3l of the relay D will release and interrupt the supply of energy to the relay XA so that contact 28 of this relay releases and initiates operation of the crossing signals to warn users of the highway of the approach of a train.

When the first train advances into section I3T track relay I 3TR is shunted and energy of 100 cycle frequency is supplied to the rails of section BI2T, and when the train vacates the clearing section, this energy feeds to the track relay BI 2TR and to the operating winding 23 of device M. Accordingly contact 38 of relay BI 2TR picks up to interrupt the supply of coded 60 cycle energy to section AI2T, while contact 3| interrupts' the supply of energy to the code transmitter CT. In addition, device M operates to establish and interrupt the circuit of the primary winding of transformer ST at a rate such that energy of 100 cycle frequency is induced in the secondary winding of this transformer, and this energy is supplied to track transformer AI2TT over the circuit including front contact 30 of track relay BIZTR.-

On the supply of steady 100 cycle energy to the track relay G its contacts remain picked up and energy is n longer supplied through the decoding transformer AIBDT to the relay H and the contacts of this relay become released. On release of contact 38 of this relay the circuit shunting the winding of relay AIETR is interrupted and thereupon the contacts of this relay pick up. e

On release of contact 3'I of relay H the supply of energy to the relay is interrupted, but the supply of energy to this relay is reestablished on` picking up of contact 32 of relay AI2TR, and the relay XA is of a type which is slow in releasing so that its contact 28 remains picked up dur-- ing this momentary interruption in the supply of energy to the relay winding.V Accordingly the crossing signals XA remain inactive at this time. In addition, on picking up of the contacts of relay AIZIR operation of the alternator AIZTAv is discontinued, while the circuit for supplying 60l cycle energy from the line transformer AIZTB to the track transformer IITT is established.

Accordingly, if while section I3T is occupied a second or following train enters either the approach section AI 2T or the clearing section BI 2T' the cab signal apparatus on the train will oper-- ate to provide the caution indication, while trackl relay AI2TR will release and its contact 32 will interrupt the supply of energy to the relay XA4 so that this relay releases and initiates operation of the crossing signals.

When the first train vacates section I3T the track relay ISTR picks up and the energy supplied to section BI2T is changd from 100` cycle In addition, it will be seen that apparatus embodying my invention provides for a special formof energy in the approach section to a highway crossing to discontinue operation of the crossing.

signals without producing a proceed cab signaly or changing the energy supplied to the adjacent section in the rear.

It will be seen also that in each modification of the invention alternating current energy of one frequency supplied from a commercial source of energy is employed to provide the clear indication, while energy of a different frequency supplied from such source by alternators is employed to provide the caution indication. The alternators are so controlled as to operate only when current is required from them, and as this is only a small part of the time, the life of the alternators is prolonged to the maximum.

In addition, it will be seen that each modication incorporates means at the cut section for relaying or repeating to the rails of the section in the rear of the cut energy of the same frequency as is supplied to the rails of the section in advance of the cut.

Although I have herein illustrated and decri-bed only two forms of railway signaling system embodying my invention, it is understood that various changes and modifications may'be made therein within the scope oi the appended claim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In combination, a stretch of railway track intersected by a highway and comprising a signal approach section and a signal clearing section, a crossing signal for the intersection, means governed by traffic conditions in advance of said clearing section for supplying to the rails of said clearing section train governing energy comprising continuous alternating current of a first or a second frequency, a track transformer having its secondary Winding connected across the rails a coding device having a contact effective When the device is energized to periodically establish a circuit to supply energy from said source of unidirectional current tosaid track transformer primary, the rate of operation of said coding device contact being such that the frequency of the energy induced in the track transformer secondary winding when current is supplied to the transformer primary Winding over the circuit controlled by said coding device is substantially lower than that of the train governing energy, said control relay being effective when released to establish a circuit to supply energy to said coding device, a rst track relay receiving energy over the rails of said approach section through a rst transformer and a second track relay receiving energy over the rails of said approach section through a second transformer, the first relay and transformer being proportioned so that said relay is picked up when and only when energy of the train governing frequencies is supplied to said transformer, the second relay and transformer being proportioned so that the relay is picked up when energy of either train governing frequency or said lower frequency is supplied to said transformer, said first relay controlling the supply of train governing energy to the rails of the adjacent section in the rear, said second relay controlling said crossing signal.

HOWARD A. THOMPSON. 

